Intra-vineyard heterogeneity of bacterial and fungal communities on cultivated Vitis vinifera grapes in the Atacama Desert

Understanding the microbial diversity associated with grape berries is essential for improving vineyard management and wine production, particularly in extreme environments such as the Atacama Desert. This study examined the intra-vineyard heterogeneity of bacterial and fungal communities colonising Vitis vinifera cv. Ahmeur bou Ahmeur grapes cultivated under a hyper-arid environment. Grape samples were collected from individual vines, and microbial assemblages were characterised using high-throughput sequencing of the 16S rRNA and ITS regions. Results revealed marked heterogeneity among vines within the same vineyard, with fungal communities showing greater variability than bacterial ones. Fungal assemblages were dominated by Starmerella, Hanseniaspora, Malassezia, and Cladosporium, whereas bacterial communities were mainly composed of Gluconobacter, Tatumella, and Asaia. Alpha and beta diversity analyses demonstrated significant differences in microbial composition among vines, indicating strong plant-specific signatures. These results provide new insights into the fine-scale heterogeneity of grape-associated microbiota in desert viticulture and highlight the importance of considering individual plants as ecological units shaping the microbial dimension of terroir.